Three port transceiver

Abstract

An optical coherent transceiver comprising a polarization and phase-diversity coherent receiver and a polarization and phase-diversity modulator on the same substrate interfaced by three grating couplers, on grating coupler coupling in a signal, one grating coupler coupling in a laser signal, and a third grating coupler coupling out a modulated signal.

The invention claimed is: 
     
       1. An optical transceiver comprising:
 a modulator and a photodiode formed in a photonic integrated circuit on a first substrate; 
 a first fiber coupler formed on the first substrate and arranged to receive laser light; and 
 waveguides formed in the photonic integrated circuit connecting the first fiber coupler to an input of the modulator and to an input of the photodiode. 
 
     
     
       2. The optical transceiver of  claim 1 , wherein the first fiber coupler is a grating coupler. 
     
     
       3. The optical transceiver of  claim 2 , wherein the grating coupler is a 1-D grating coupler. 
     
     
       4. The optical transceiver of  claim 1 , wherein the modulator and the photodiode are located in opposite halves of the first substrate. 
     
     
       5. The optical transceiver of  claim 1 , further comprising:
 a second fiber coupler coupled to an output of the modulator; and 
 a third fiber coupler coupled to the input of the photodiode. 
 
     
     
       6. The optical transceiver of  claim 5 , further comprising at least one variable optical attenuator connected between the third fiber coupler and the input of the photodiode. 
     
     
       7. The optical transceiver of  claim 5 , further comprising an optical 90° hybrid connected between the third fiber coupler and the input of the photodiode. 
     
     
       8. The optical transceiver of  claim 7 , wherein the optical 90° hybrid is further connected between the first fiber coupler and the input of the photodiode. 
     
     
       9. The optical transceiver of  claim 5 , wherein the second fiber coupler and the third fiber coupler are both formed on the first substrate. 
     
     
       10. The optical transceiver of  claim 1 , wherein the modulator comprises a nested Mach-Zehnder modulator that includes a thermooptic phase shifter. 
     
     
       11. The optical transceiver of  claim 1 , further comprising a laser having an output coupled to the first fiber coupler. 
     
     
       12. The optical transceiver of  claim 11 , wherein a first portion of the laser is formed on the first substrate and a second portion of the laser is formed on a second substrate. 
     
     
       13. The optical transceiver of  claim 12 , wherein the first substrate comprises silicon and the second substrate comprises indium phosphide. 
     
     
       14. The optical transceiver of  claim 12 , wherein the first portion of the laser comprises a wavelength locker and the second portion of the laser includes a semiconductor optical amplifier. 
     
     
       15. The optical transceiver of  claim 1 , further comprising a second fiber coupler, a third fiber coupler, and a fiber assembly having three optical fibers coupled, respectively, to the first, second, and third fiber couplers of the optical transceiver. 
     
     
       16. The optical transceiver of  claim 1 , wherein the waveguides comprise first and second waveguides, the first waveguide connecting the first fiber coupler to the input of the modulator and the second waveguide connecting the first fiber coupler to the input of the photodiode. 
     
     
       17. The optical transceiver of  claim 16 , further comprising a first beam splitter having an input, a first output and a second output, the input of the first beam splitter being connected to a third waveguide coupled to the first optical port, the first and second outputs of the first beam splitter being connected to the first and second waveguides, respectively. 
     
     
       18. The optical transceiver of  claim 17 , further comprising a second beam splitter coupling the first beam splitter to the first optical port.